Change a field en masse in multiple find requests

I routinely run a FIND that has multiple find requests, maybe 10 or 15, sometimes more. What is new each time is the contents of one field common to each request, a date field. When I run it each time, I must change the one criterion that is new--and common to all--in each and every request. It's tedious and time consuming. Is there a way to enter the new date to find by entering it one time somewhere somehow?